Although certainly not limited to communication between implanted devices and external control units, the method finds particular application and advantage when used in the implantable arts field. So for example, the field of bionics is a discipline focusing on the application of advanced technologies to biological systems. In other words, bionics relates to physiological processes that are replaced or enhanced by electronic components. Generally speaking, a bionic is a manufactured device or engineered tissue that substitutes for, or augments, the function of a natural limb, organ or other portion of a biological body. Significant strides have been made in the field of bionics and research in bionics offers the greater possibility of restoring function to impaired and damaged biological systems.
An example application of bionic devices includes sensing and stimulating nerves in the body, such as is described in U.S. Pat. No. 6,829,508, entitled “Electrically sensing and stimulating system for placement of a nerve stimulator or sensor”, which is hereby incorporated by reference. Additional examples of Bionic devices include restoration or improvement of damage hearing such as is described in U.S. Pat. No. 6,572,531 entitled “Implantable Middle Ear Implant, and U.S. Pat. No. 6,648,813, entitled “Hearing Aid System Including Speaker Implanted In Middle Ear”, which are both incorporated herein by reference.
Current developments in the field present a number of opportunities for improving the quality of life with the undertaking of new and exciting research in such areas as drug delivery systems for chronic disabilities, neuromuscular stimulation devices that enable the activation or enhancement of motion to replace lost or impaired motor control, microstimulators to treat chronic disorders of the central nervous system, as well as many others.
An example body implantable device is described in U.S. Pat. No. 6,185,452 entitled “Battery Powered Patient Implantable Device”, incorporated herein by reference, which describes body implantable devices for performing stimulation of body tissues, sensing of various body parameters, and communication to other devices external to the patient's body. The implanted devices can utilize a wireless communication means, such as described in U.S. Pat. No. 7,237,712 entitled “Implantable Device and Communication Integrated Circuit Implemented Therein”, incorporated herein by reference. The wireless communication of the body implanted device can be facilitated by an antenna such as described in U.S. Pat. No. 6,804,561, entitled “Antenna For Miniature Implanted Medical Device”, which is incorporated herein by reference. Throughout the art however, there is almost no discussion relating to signal interference removal for a type of communication signal described as the conventional TDMA signal which has application for certain implantable devices communicating with an external device. It is known that TDMA signals may have widely varying dynamic ranges, for example, as much as 50 db. An attempt was made to solve such problem as described in U.S. Pat. No. 5,741,591, however, there were severe restrictive assumptions placed on both the user wideband signal and the interfering signal to render the teaching relatively ineffectual as a viable solution strategy. Two assumptions for example, were that the interfering signal was a constant continuous wave signal and that the user signal amplitudes did not vary appreciably one from another.